1. Field of the Invention
The present invention relates generally to the art of decorative articles, such as moldings used in the manufacture of picture frames. More specifically, the present invention relates to an embossing apparatus and method used in sequence with a laminator which applies a covering wrap about a molding substrate.
2. Description of the Prior Art
The art of manufacturing picture frames is ancient by origin. Processes are still being developed to this date to accomplish the purposes originally intended, i.e. to support and enhance an art work presented to an observer. Early frames were manufactured by hand carving wood, a process which continued well into the renaissance.
One subsequent technique involved the use of plaster for coating wood substrates to allow the artist to emboss or form deep relief, in giving the same look as carved wood or marble with much less work or cost.
Subsequent artisans also developed the technique of layering plaster in wooden forms using burlap, with plaster layers built up one layer at a time and formed with a form tool or drag. This process was used to make moldings for buildings and quickly was adapted for use in picture frames. The plaster was frequently covered with gold leaf, and covered with shellac or varnish. Extremely intricate moldings were created, but obviously they were very expensive, even centuries ago.
The technology of frame making remained somewhat static until the Eighteenth Century, when advances were made in furniture manufacture. Craftsmen developed new techniques for making joints, and the precision of picture frame moldings became markedly improved. The Industrial Revolution led to specially designed machines to assist in the making of frames.
The development of the camera increased further the demand for less expensive picture frames which, as recently as the 1930's, still were beyond the means of the masses. Machines for duplicating the work of carvers were developed. The cost of labor was reduced, but the cost of the material was still a major factor in the overall cost. More recently, manufacturers have looked to alternate methods that use less expensive materials. Instead of rare woods, such as mahogany, teak and rosewood, manufacturers resorted to less expensive woods, such as poplar, oak and birch. Cheaper wood was frequently stained to imitate more expensive wood.
Eventually, even the cost of common wood became a larger factor in the cost of mass produced frames. With the development of plywood in the 1940's, the use of veneers became popular, and more expensive wood veneers were glued to less expensive wood by both furniture and picture frame manufacturers. Flake board or particle board became more popular in later years, and to drive costs down even more, manufacturers began to experiment with laminating paper to wood. The paper could be obtained in any pattern. Machinery which was originally developed for laminating veneer to wood was modified to laminate paper and other materials to the wooden substrates.
The most common substrate used in the molding industry today is medium density fiberboard, known as "MDF". Its use began to lower prices in the furniture industry and it was very popular in the ready-to-assemble furniture markets. Frame manufacturers readily adapted MDF to their uses. The decoration that was most commonly used on such moldings was paper, with the paper designs changing as frequently as the artists desired. Little was done to improve the finish, durability or functionality of the papers used in laminating.
It is also known that a design can be burned into wood, using embossing rollers. An example of this process is shown in U.S. Pat. No. 3,764,767 issued Oct. 9, 1973 to Randolph for "Induction Embossing". In this process, a wheel which can be adjusted in temperature using induction heating, is driven into contact with a molding substrate to impress upon it a particular pattern. Such process is applied directly to the wood, and it has never been suggested that such processes could be used on MDF or other substrates which have been laminated with paper.
Other methods for preparing ornamentation include the hot stamping technique shown in U.S. Pat. No. 3,540,960 issued Nov. 17, 1970 to Widigs for "Method Of Ornamenting A Wood Article With Metal Foil". A tape of ornamentating material is placed between the article and a set of rollers, the tape preferably comprising a strip of plastic material having a thin layer of ornamentation, for example gold leaf or the like, thereon. The metal layer of the tape adheres to and covers an impression made by the rollers, thereby creating a pleasing ornamental effect and the carrier tape itself is removed and discarded.
Several other patents illustrating ornamentation of moldings include U.S. Pat. No. 1,606,863 issued Nov. 16, 1926 to Zimmerman for "Picture Frame And Method Of Producing The Same" (showing pressure embossing of corner joints); U.S. Pat. No. 366,835 issued Jul. 19, 1887 to Hogan for "Picture Frame"; U.S. Pat. No. 5,304,412 issued Apr. 19, 1994 to Wang for "Extruded Plastic Article With A Decorative Plastic Strip" (showing the bonding of a decorative plastic strip to a plastic frame member).
In addition to paper for laminating processes, other covering materials have been employed in the prior molding art, including foil, plastic, cloth or wood veneer. Furthermore, in typical laminating operations, glues are applied to a depth of about 11/2 mils. Typically, the glues are hot melts. Paper commonly used in the process is 40 weight (forty pounds per 1,000 square feet), while 4 mil. vinyl is frequently used when a plastic material is desired. The particular shape of the molding can be any of the hundreds of profiles known in the art.
While the techniques of laminating and of embossing have been separately employed to make decorative picture frames, it has not been suggested to combine the two in a single operation, probably because most embossing processes known in the art would be detrimental to the paper. A technique which would allow the lamination of inexpensive substrates with covering material and which would also allow for the creation of an embossed pattern thereon would represent a significant advance in this technology.